STROMATOPOROIDEA—ANTHOZOA. 47 



with cystose tabulae and a peripheral vesicular structure character- 

 ize the fossil. Ordovicic. 



23. B. nodulosa Bill. (Fig. 74.) Ordovicic. 

 Cylindrical, with oblong, oval or subtrian- 

 gular blunt-pointed tubercles, sometimes ar- 

 ranged in vertical rows. 



Trenton and Cincinnati groups Anticosti 

 and Kentucky. 



24. B. undulata Bill. Ordovicic. 



Fig. 74- Beatriceano- Surface sulcated longitudinally by short, 



dulosa, transverse section . . ... r _ .. 



, 4 , , irregular, wave-nke furrows, from two lines to 



showing inner tube and & ' ' 



cystose character (after ° ne mcn across, according to size of specimen. 

 Nicholson). Cincinnati group of Anticosti. 



Class Anthozoa or Actinozoa (Corals). 

 Marine animals ranging from low water to depths of 1,500 

 fathoms, but chiefly at home in tropic seas above the fifty fathom 

 line. The animal or polyp may be simple, or give rise by budding 

 or division to a compound polyparium, in which the individuals 

 or polypites may be distinct or confluent. 



The corallum or hard structure secreted by these animals is 

 simple or compound. Typically each coral is furnished with a cir- 

 cumferential wall, and radiating lamellae or septa, though either 

 the one or the other may be much reduced or even absent. The 

 wall may be an independent structure, growing up like the septa 

 from the bottom of the corallum (theca), or it may be formed of 

 the thickened and fused outer ends of the septa (pseudotheca). 

 The outer ends of the septa are frequently continued beyond the 

 wall as costce. Often an outer more or less wrinkled envelope or 

 epitheca occurs, which shows concentric lines of growth. Between 

 the septa are various endothecal structures, such as cross plates or 

 dissepiments, cross-bars or synapticulce, or continuous floors or 

 tabnlcB which extend across the whole coral. In some cases the 

 interior consists of a spongy mass, the septa being very rudimen- 

 tary (CystipJiyllinii). The septa may be smooth, or furnished with 

 granules, or reinforced by vertical beams, which on cross section or 

 in the calyx of the coral, look like short regular bars (carina) cross- 

 ing the septum, and extend a short distance on each side (Heliopliyl- 

 lum). The upper edges of the septa in the calyx may be spinous, 

 or smooth. A central rod or columella is frequently present, and 



